Gallery Custom Links allows you to link images from galleries to a specified URL. Tested with WordPress Gallery, Gutenberg, the Meow Gallery and others.
Two fields are added to your images, in your Media Library: Link URL and Link Target. If, at least, the Link URL is set up, this image will link to that URL every time it is used within a gallery. Lightbox will be automatically disabled for those images.
It currently works with the native WP Gallery, the Gutenberg Gallery, and the Meow Gallery. It should actually work with any gallery plugin using the ‘gallery’ class and Responsive Images (src-set). Let me know if you would like more galleries to be supported, it should be easy. It does not work with NextGEN, as it does not work with Responsive Images.
The motivation to build this plugin came from my users who had issues trying to use WP Gallery Custom Links. I realized that this plugin was working extremely well with the standard gallery, but would require too much rewriting for Gutenberg and other galleries, hence the creation of this plugin. I hope it will help.